September in the hills with Chris Horne and Barbara Mitcalfe

Passiflora tetranda, kōhia, NZ passion flower, NZ passion fruit

Showing leaves, flowers, and at the top, a tendril Photo: Jeremy Rolfe

If you have seen woody, cobra-like coils, up to 14 cm in diameter, curling on the forest floor, and then climbing into the canopy to reach the light, you will have seen this endemic vine. Kōhia grows in lowland and montane forests, from near North Cape to Banks Peninsula. It spreads over the sun-lit canopy, reaching the tops of trees 30-40 m high, as reported in some forests on the Hauraki Plains.

Kōhia is a tendril-climber, like the sweet pea, cucumber and grapevine. It produces slender, delicate tendrils up to 10 cm long, from its stems. When first formed, a tendril is almost straight, and as it grows it slowly waves around. When it encounters the trunk or branch of a potential supporting plant, the tendril's tip wraps around it, thus securing support. Once the tip has attached to it, the remaining part of the tendril coils into two spirals, one left and the other right, which increase its elasticity, drawing the stem closer to the support. (Compare this mechanism with that used by bush lawyer, a ‘hook climber’ – see August 2012 article).

Kōhia’s coils are flexible trunks, round in cross-section, and its branchlets are very slender. The leaves are alternate, lance-shaped, 5-10 cm long by 2-3 cm wide, leathery, dark green and glossy above, and paler below, with slightly wavy edges.

Kōhia is dioecious, so has male and female flowers on separate plants. Between October and March, the yellowish-green female flowers produce pear-shaped, bright orange fruit, 2-3 cm in diameter, which contain wrinkled seeds in a red pulp. We trampers find the fruit disappointingly dry, but birds, possums and rats seek the pulp, so we sometimes see the torn remains of kōhia fruit strewn on the forest floor.

Use

Like so many of our indigenous plants, kōhia had numerous uses in pre-European times. Expert at making lashings out of vines, Māori used kōhia to bind fence posts, platforms and the frames of whare. Because kōhia wood burns very slowly, they used partially hollowed-out sections of its sturdy stems for carrying fire when travelling. They also made a scented body oil by crushing, steaming and pressing kōhia seeds to extract the oil which they then perfumed with the leaves of aromatic plants. Used medicinally, it was applied to soothe sores and wounds